Sealed combustion chamber natural draft, outside wall furnace

ABSTRACT

A furnace fired by gas or other fluid fuel and adapted for mounting through an outside wall of an enclosure to be heated, such as a recreational vehicle, has a combustion system sealed from the interior of the enclosure and including a burner and burner chamber, combustion chambers and flues formed as a heat exchanger, and vent structure arranged to be exposed to the atmosphere to provide both draft for the burner and venting for the flues. The vent structure provides for lower than exterior pressure at the burner during all stages of firing and all wind conditions and comprises baffles arranged between the burner and the flue exhaust openings in a vent chamber formed behind an exterior face plate that is provided with vents, preferably in the form of louvers, in an upper section thereof and with ports in a lower section thereof. The ports confront a downwardly and inwardly sloping baffle in the vent chamber, which serves as an air scoop. Between the louvers and the ports the face plate is imperforate and configurated as an airfoil, and below the ports but above the burner within the vent chamber a rain gutter is preferably arranged to keep the burner and combustion chambers dry. The face plate is apertured below the ports for discharging any moisture collected by and draining from the rain gutter and for serving as auxiliary exhaust vents under certain wind conditions. For aiding in the maintainance of proper draft and also for further protecting against entry of moisture to the vent chamber, the louvers in an intermediate portion of the louvered section of the face plate are advantageously double, projecting both outside and inside the furnace.

United States Patent [191 Jackson et al.

[ 1 Mar. 18, 1975 SEALED COMBUSTION CHAMBER NATURAL DRAFT, OUTSIDE WALL FURNACE [75] Inventors: George W. Jackson, Salt Lake City;

Dennis N. Dacey, Riverton; Paul W. Jackson, Granger, all of Utah [73] Assignee: Hydro Flame Corporation, Salt Lake City, Utah [22] Filed: Jan. 7, 1974 [21] Appl. No.: 431,474

[52] U.S. Cl. 126/110 R, 126/116 R, l26/llO B [51] Int. Cl. F24h 3/00, F23j 11/00 [58] Field of Search 126/110 R, 116 R, 110 B,

126/99 R, 85 B, 116 B, 307 R [56] References Cited UNITED STATES PATENTS 2,693,914 11/1954 Payne 126/1 16 R 2,982,282 5/1961 Fertig l26/l l0 B 3,144,90l 8/l964 Meek l26/ll0 B 3,294,082 l2/l966 Norris l26/l 10 R 3,394,696 7/1968 Cooper 126/110 R 3,504,66l 4/l970 Morris et al. 126/116 R 3,680,54l 8/1972 Honaker, .lr. 126/1 l0 B 3,724,442 4/1973 Gurney et al. l26/l 10 B Primary Examiner-lohn J. Camby Assistant Examinerl-lenry C. Yuen Attorney, Agent, or Firm-Mallinckrodt & Mallinckrodt [57] ABSTRACT A furnace fired by gas or other fluid fuel and adapted for mounting through an outside wall of an enclosure to be heated, such as a recreational vehicle, has a combustion system sealed from the interior of the enclosure and including a burner and burner chamber, combustion chambers and flues formed as a heat exchanger, and vent structure arranged to be exposed to the atmosphere to provide both draft for the burner and venting for the flues. The vent structure provides for lower than exterior pressure at the burner during all stages of firing and all wind conditions and comprises baffles arranged between the burner and the flue exhaust openings in a vent chamber formed behind an exterior face plate that is provided with vents, preferably in the form of louvers, in an upper section thereof and with ports in a lower section thereof. The ports confront a downwardly and inwardly sloping baffle in the vent chamber, which serves as an air scoop. Between the louvers and the ports the face plate is imperforate and configurated as an airfoil, and below the ports but above the burner within the vent chamber a rain gutter is preferably arranged to keep the burner and combustion chambers dry. The face plate is apertured below the ports for discharging any moisture collected by and draining from the rain gutter and for serving as auxiliary exhaust vents under certain wind conditions. For aiding in the maintainance of proper draft and also for further protecting against entry of moisture to the vent chamber, the louvers in an intermediate portion of the louvered section of the face plate are advantageously double, projecting both outside and inside the furnace.

10 Claims, 7 Drawing Figures PMENTED MAR l 8 I975 sum 2 or 3 llIIIHIIIIEH"'IIHIIIIllIIIIIIIIIIIIHIIIIIIIIlllIlIllllIlIIl SEALED COMBUSTION CHAMBER NATURAL DRAFT, OUTSIDE WALL FURNACE BACKGROUND OF THE INVENTION 1. Field The invention is in the field of fluid-fuel-fired, sealed combustion chamber furnaces of forced air, interior circulative type for exterior wall mounting in a manner such as to have natural gravity draft directly from and to vent products of combustion directly to the outside atmosphere.

2. State of the Art Gas-fired outside-wall-mounted furnaces for heating recreational vehicles during travel as well as when standing still are well known and extensively used. These have been constructed in various ways to achieve, so far as possible, proper draft under all conditions and to guard against extinguishment of the pilot light. The desired results have been achieved with varying degrees of success, though the maintaining of proper draft during all weather and traveling conditions has remained a very real problem.

SUMMARY OF THE INVENTION In accordance with the present invention, the results heretofore recognized as desirable and sought for ar achieved to a most satisfactory extent.

A feature of the invention is the provision of baffle structure within a vent chamber forming part of the combustion system of the furnace and confronting, through vent structure at one end of the furnace, the exterior of the recreational vehicle or other enclosure in which the furnace is installed. The vent chamber communicates with the atmosphere through a vented face plate, which is preferably configurated in cooperative relationship with a downwardly and inwardly sloping baffle plate, usually of an arcuate configuration at its upper and lower ends, that serves in effect as an air scoop. A fluid-fuel burner is provided below the baffle plate in a burner chamber that underlies one or more combustion chambers and flues of a heat exchanger and is arranged to receive natural gravity draft from the vent chamber. The heat exchanger flues are arranged to discharge gaseous products of combustion into the vent chamber. Both burner and combustion chambers are advantageously protected from drops of rain or other moisture, that may enter the furnace through the face plate, by means of an overhead rain gutter within the vent chamber and below the baffle plate.

A louvered section of the face plate is provided in an upper portion thereof, and a ported section is spaced therebelow confronting the air scoop baffle. Between these two sections is a preferably imperforate portion, advantageously configurated as an airfoil for directing atmospheric air inwardly toward and through the ports of the ported section of the face plate. By reason of the air scoop baffle, inward flow of air ensures a pressure within the furnace that is always lower than the outside pressure.

The protective rain gutter is arranged in the vent chamber above the burner draft opening, so as to discharge laterally of such opening. Drain holes are provided in the face plate, below the ported section thereof, through which collected moisture is discharged to the outside of the furnace. These drain holes may also participate in venting of products of combustion under certain wind conditions.

As an aid to establishing and maintaining proper natural draft conditions in the furnace and to further protect against entry of moisture to the vent chamber immediately above the burner draft opening, an intermediate portion of the louvered section of the face plate is advantageously doubly louvered, there being pairs of louvers projecting outside and inside, respectively.

THE DRAWINGS The best mode presently contemplated for carrying out the basic inventive concepts is illustrated in the accompanying drawings, in which:

FIG. 1 is a view showing the wall furnace of the invention in perspective, looking from the front toward the exterior face plate of the furnace;

FIG. 2, a view in elevation of the burner end of the furnace of FIG. 1, which confronts the atmosphere when the furnace is installed through an outside wall of an enclosure to be heated, the face plate having been removed;

FIG. 3, a longitudinal vertical section taken on the line 33 of FIG. 1 and drawn to a smaller scale;

FIG. 4, a fragmentary vertical section taken on the line 44 of FIG. 1 and drawn to a considerably larger scale;

FIG. 5, a fragmentary vertical section taken on the line 5-5 of FIG. 2 and drawn to a somewhat smaller scale than that of FIG. 4;

FIG. 6, a transverse vertical section taken on the line 66 of FIG. 3 and drawn to the same scale; and

FIG. 7, a fragmentary horizontal section taken on the line 77 of FIG. 3 and drawn to the same scale.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT As constructed in accordance with the best mode presently contemplated of carrying out the inventive concepts defined by the claims, the furnace of the invention comprises a heat exchanger 10, see particularly FIG. 3 and 6, in the form of an assembly of combustion chambers and flues made up of a plurality (in the present instance three) of outwardly timed and dimpled conduits 11 providing, internally thereof, respective combustion and flue passages 1 la, FIG. 3, leading from a burner chamber 12 to a vent chamber 13. Each of the conduits 11 is preferably formed by welding together (along outwardly protruberant, face-to-face flanges llb) identical concave stampings of sheet steel placed together in face-to-face relationship. The several conduits are connected at their lower ends to the upper wall 12a of the structure defining burner chamber 12, as by welding or lock seaming, and, at their upper ends, pass through the rear wall 13a of vent chamber 13, so that the combustion and flue passages 11a are in communication with both the burner chamber and the vent chamber. The wall structure defining vent chamber 13 is preferably of pan formation, as illustrated, with a pcripheral flange 13c extending outwardly from and around peripheral side wall 13b.

As so fabricated, heat exchanger 10 and the structure defining burner chamber 12 and vent chamber 13 are mounted in a housing 14 that is provided, at its outer end, with a uniquely ported and configurated face plate 15 and, at its inner end, with a face plate I6, FIGS. 1 and 3, in the form of a louvered grill.

Although heat exchanger 10 is shown as made up of several combustion chambers and flues, it should be understood that a single combustion chamber and flue could be utilized. Also, it should be realized that a combustion chamber is made up of a combustion and flue passage 11a in conjunction with burner chamber 12.

A propane gas burner assembly 17 is mounted within burner chamber 12 and has elongate burner members 170, FIGS. 3 and 7, underlying the respective conduits 11 so as to direct burning fuel upwardly into and through the combustion and flue passages 11a. Conventional means 18 are provided for controlling the supply of gas to burner members 17a through a supply pipe 19. Such means 18 serves also to control supply of gas to a pilot light 20, FIG. 7, through a pipe l9l in the usual manner.

Housing 14 is partitioned transversely by a wall 21 to provide compartments 22 and 23, FIG. 3, the former communicating with the exterior of the housing through louvered grill 16 applied to its otherwise open end and the latter being open to receive the wall structure of vent chamber 13 as an end closure therefor. An air-circulating blower 24 is mounted in compartment 22 on wall 21 to pull in interior through grill 16 and to discharge it into compartment 23 in heat-exchange relationship with the finned and otherwise protruberant exterior wall faces of heat exchanger conduits 1 1. Suitable punch-out portions 14a, FIG. 1, are provided in the side walls of housing 14 within the extent of heat exchange compartment 23 to enable selective connection with air ducts leading to various portions of the enclosure to be heated. A gas supply pipe 18a, FIG. 7, connects with a main supply line (not shown) through port 25.

Peripheral flange 13c of vent chamber 13 fits against the walls of housing 14 to close off the forward end of heat exchange compartment 23 and ensure circulation of interior air through such heat exchange compartment entirely free of products of combustion. A gasket 17-1, FIG. 7, is interposed between rear supporting wall 17c of burner assembly 17 and partition wall 21, and a similar gasket 13-1 is interposed between wall 13a, and the forward end of the structure defining burner chamber 12.

As installed in heat-exchange compartment 23, together with the wall structures defining burner chamber 12 and vent chamber 13, heat exchanger constitutes a sealed unit open only for draft air intake to the combustion chambers thereof and discharge of products of combustion from the flues thereof. Blower 24 serves to circulate air from the interior of the vehicle into, through, and out of heat exchange compartment 23 by way of louvered grill l6 and blower chamber 22.

The furnace is adapted to be mounted through an ouside wall of an enclosure to be heated, usually the side wall of a recreational vehicle, with its ported face plate substantially flush with the exterior surface of such wall and exposed to and communicating with the atmosphere, and with its louvered grill 16 exposed interiorly of the enclosure to be heated.

Within vent chamber 13, a heat shield 26, FIG. 4, is mounted on wall 13a in spaced relationship with peripheral wall 13b and is apertured for the passage therethrough of horizontal flue members 11c which terminate in box baffle 27 and are welded to wall 13a. Such box baffle is spaced from heat shield 26 and is open laterally with forward exposure, as at 2711, FIG. 2. An elongate aperture 28, FIG. 3, in the bottom of box baffle 27 leads downwardly into the space 28a behind a downwardly and inwardly sloping baffle plate 29, advantageously having at least its upper and lower ends arcuate, as shown, and serving in effect as an air scoop. It should be noted that baffle plate 29 defines opposite lateral openings, see the opening 290, FIG. 2, leading from space 28a, for the outflow of any exhaust gases that may flow downwardly through aperture 28.

Below baffle plate 29 and above a burner draft aper ture or opening 30, FIGS. 2 and 3, in wall 130, through which aperture burner manifold 1712 projects, is a gabled rain gutter 31 for catching any droplets of rain or other moisture that might enter vent chamber 13 through the openings of face plate 15 or drip from baffle plate 29. Such rain gutter discharges laterally of aperture 30 and of a lower baffle plate 32 serving also as a rain shield. Such baffle plate 32 is itself apertured at and along its bottom margin, as at 33, to permit drainage of any collected moisture.

Face plate 15, through which vent chamber 13 communicates with the atmosphere, is applied to housing 14 in face-to-face relationship with peripheral flange 14b thereof. As best shown in FIGS. 1 and 4, it is provided with vents in the form of louvers 34 in an upper section thereof confronting box baffle 27 and the lateral openings 27a thereof in vent chamber 13, see FIG. 3. The louvers 34 in an intermediate portion of the louvered section of face plate 15 are preferably double, projecting both outside vent chamber 13 in normal manner and also inside, as at 34a. This has been found to both aid in the maintenance of proper draft conditions and to further protect against entry of rain and other atmospheric moisture into the vent and burner chambers.

Lower than atmospheric pressure is constantly maintained in vent chamber 13 adjacent to burner draft aperture 30 and burner assembly 17 by means of an airfoiI-configurated, imperforate, intermediate section 15b of face plate 15 lying between the upper louvered section of such face plate and a lower section provided with a series of ports 35. Such airfoil section 15b directs atmospheric air, blowing against the exterior face of the wall in which the furnace is installed, inwardly toward and through ports 35. To further enhance flow of air into vent chamber 13 and to aid in ensuring lower pressure inside than outside at all times, the ports 35 are located in confronting relationship with air scoop baffle 29.

Projecting inwardly of vent chamber 13 from face plate 15 immediately below ports 35, a rain lip 36, FIG. 4, is preferably provided to direct moisure entering through the ports into rain gutter 31.

Spaced below ports 35 in face plate 15 is a series of drain holes 37 located in confronting relationship with rain shield 32 so as to drain collected moisture from the bottom of vent chamber 13 and to serve as auxiliary exhaust vents under certain wind conditions. Thus, when wind is blowing at approximately fifteen miles an hour or greater and at any angle against (as opposed to parallel along) the outside wall of the enclosure in which the furnace is installed, a portion of the exhaust gases are actually vented to the atmosphere through the holes 37. This is due to the action of airfoil 15b in conjunction with the action of scoop 29 and is highly significant in maintaining proper draft conditions during weather conditions that tend to smother both pilot and main burner flames in conventional furnaces of this type.

Although the combination of air scoop with airfoil is much preferred for most instance of use of the invention, it is possible to obtain limited benefits against smothering of pilot and burner flames under various weather conditions by use of the air scoop baffle 29 alone, i.e., without utilizing in conjunction therewith an airfoil formation for the imperforate portion b of the face plate 15. However, it should be realized that this will normally yield only partial benefits of the present invention.

Whereas this invention is here illustrated with respect to a presently preferred specific embodiment thereof, it is to be understood that various changes may be made without departing from the generic inventive concepts defined by the claims that follow:

We claim:

1. A fluid-fuel furnace for mounting through an exterior wall of an enclosure to be heated, comprising a housing having a vented end adapted for exposure to the atmosphere; wall means internally of said housing providing a vent chamber at said vented end and a heated exchange compartment next to the vent chamber and closed off from air flow communication therewith; heat exchange structure within the heat exchange compartment and defining internally thereof one or more lower combustion chambers opening into one or more upper exhaust flues for gaseous products of combustion, said flues opening into the upper part of the vent chamber through said wall means; additional wall means below the heat exchange structure and defining a burner chamber opening into said one or more combustion chambers and having a draft-opening through the first-named wall means into the vent chamber; a fluid fuel burner within the burner chamber; baffle means within the vent chamber comprising a downwardly and inwardly sloping air scoop baffle plate positioned between the flue openings in the vent chamber and said draft opening; a face plate providing said vented end of the housing, said face plate having exhaust vents formed through an upper section thereof above said baffle plate, and additionally having ports formed through a lower section thereof that is spaced below said upper section, to provide outside draft air for said burner; means for supplying said burner with a fluid fuel; and means for flowing air from within said enclosure into, through, and out of said heat exchange compartment.

2. A furnace in accordance with claim 1, wherein the baffle plate is arcuate along its upward and downward extent at least at its upper and lower ends.

3. A furnace in accordance with claim 1, wherein there is an imperforate section between the upper and lower sections of the face plate 4. A furnace in accordance with claim 3, wherein the baffle plate defines a space rearwardly thereof that is open laterally; and wherein the baffle means further comprises a box baffle covering the flue openings into the vent chamber and having lateral and bottom exhaust openings leading directly into the vent chamber and into said space behind the baffle plate, respec tively.

5. A furnace in accordance with claim 4, wherein a heat shield is interposed between the box baffle and the wall means through which the vent openings pass, the flue-defining portions of the heat exchangers terminating in the box baffle.

6. A furnace in accordance with claim 5,, wherein the baffle plate is arcuate along its upward and downward extent at least at its upper and lower ends.

7. A furnace in accordance with claim 1, wherein the face plate is additionally formed with openings near its bottom and below the ported lower section thereof, said openings providing supplemental exhaust venting when atmospheric conditions require it.

8. A furnace in accordance with claim 7, wherein a laterally extending rain gutter is provided within the vent chamber below the downwardly and inwardly sloping baffle plate and above the draft opening leading into the burner chamber, the supplemental exhaust openings serving also as drains for said rain gutter.

9. A furance in accordance with claim 8, wherein a baffle plate is spaced below the rain gutter at the bottom of the vent chamber between the supplemental exhaust openings and the burner draft opening.

10. A furnace in accordance with claim 1, wherein a laterally extending rain gutter is provided within the vent chamber below the downwardly and inwardly sloping baffle plate; and drain openings are provided below said rain gutter. 

1. A fluid-fuel furnace for mounting through an exterior wall of an enclosure to be heated, comprising a housing having a vented end adapted for exposure to the atmosphere; wall means internally of said housing providing a vent chamber at said vented end and a heated exchange compartment next to the vent chamber and closed off from air flow communication therewith; heat exchange structure within the heat exchange compartment and defining internally thereof one or more lower combustion chambers opening into one or more upper exhaust flues for gaseous products of combustion, said flues opening into the upper part of the vent chamber through said wall means; additional wall means below the heat exchange structure and defining a burner chamber opening into said one or more combustion chambers and having a draftopening through the first-named wall means into the vent chamber; a fluid-fuel burner within the burner chamber; baffle means within the vent chamber comprising a downwardly and inwardly sloping air scoop baffle plate positioned between the flue openings in the vent chamber and said draft opening; a face plate providing said vented end of the housing, said face plate having exhaust vents formed through an upper section thereof above said baffle plate, and additionally having ports formed through a lower section thereof that is spaced below said upper section, to provide outside draft air for said burner; means for supplying said burner with a fluid fuel; and means for flowing air from within said enclosure into, through, and out of said heat exchange compartment.
 2. A furnace in accordance with claim 1, wherein the baffle plate is arcuate along its upward and downward extent at least at its upper and lower ends.
 3. A furnace in accordance with claim 1, wherein there is an imperforate section between the upper and lower sections of the face plate
 4. A furnace in accordance with claim 3, wherein the baffle plate defines a space rearwardly thereof that is open laterally; and wherein the baffle means further comprises a box baffle covering the flue openings into the vent chamber and having lateral and bottom exhaust openings leading directly into the vent chamber and into said space behind the baffle plate, respectively.
 5. A furnace in accordance with claim 4, wherein a heat shield is interposed between the box baffle and the wall means through which the vent openings pass, the flue-defining portions of the heat exchangers terminating in the box baffle.
 6. A furnace in accordance with claim 5,, wherein the baffle plate is arcuate along its upward and downward extent at least at its upper and lower ends.
 7. A furnace in accordance with claim 1, wherein the face plate is additionally formed with openings near its bottom and below the ported lower section thereof, said openings providing supplemental exhaust venting when atmospheric conditions require it.
 8. A furnace in accordance with claim 7, wherein a laterally extending rain gutter is provided within the vent chamber below the downwardly and inwardly sloping baffle plate and above the draft opening leading into the burner chamber, the supplemental exhaust openings serving also as Drains for said rain gutter.
 9. A furance in accordance with claim 8, wherein a baffle plate is spaced below the rain gutter at the bottom of the vent chamber between the supplemental exhaust openings and the burner draft opening.
 10. A furnace in accordance with claim 1, wherein a laterally extending rain gutter is provided within the vent chamber below the downwardly and inwardly sloping baffle plate; and drain openings are provided below said rain gutter. 